boiler
n. countablen. a large metal tank that heats water for a building. It provides hot water for your taps and keeps your home warm through radiators.
n. a closed vessel in which water or other liquid is heated, steam is generated, or any combination thereof, under pressure or vacuum, for use external to itself.
The boiler broke down, so we have no hot water.
The landlord promised to send a technician to service the gas boiler before the winter temperatures arrived.
Modern high-efficiency condensing boilers capture heat from exhaust gases that would otherwise be lost, significantly reducing the energy required to maintain a building's ambient temperature.
From boil + -er.
Shortening of boilerplate
Commonly modified by the fuel source, such as 'gas boiler', 'electric boiler', or 'oil boiler'.